Correct spelling for the English word "Mendment" is [mˈɛndmənt], [mˈɛndmənt], [m_ˈɛ_n_d_m_ə_n_t] (IPA phonetic alphabet).
The word mendment is not commonly found in the English language, and I couldn't locate any specific definition or etymology for it. It is possible that mendment may be a rare or seldom-used term or a typographical error. Without further information or context, it is challenging to provide a definitive answer on the etymology of mendment.